Scanning camera



Oct l5 1,946 F. T. SONNE Erm;

SCANN'ING CAMERA 4 Sheets-Sheet l Filed Aug. 1e, 1945 '0cL15,1946; EISQNNE ETAL 2,409,597

l SCANNING CAMERA Filed Aug. 16, 194:5 4 sheets-sheet 2 federc'ck 7.' 6017.116/- Va'o Zar 611.551,27.

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` Oct. 15, 1946.

F'. T. SONNE: E-r Al.l 2,409,597

S GANNING CAMERA `Filed Aug. 16, 1945 4 Sheets-Sheet 3 0d l5, 1946- F. T. SONNE ErAL v 2,409,597

SCANNING CAMERA Filed Aug 16,4 1943 4 Sheets-Sheet 4 EIL lugs!!! lvl OG,

Patented Oct. 15, 1946 SCANNING CAMERA Frederick Theodore Sonne, Golf, and Vctr Sussin, Chicago, Ill., assgnors to Chicago Aerial Survey Company, Chicago, Ill., a corporation of Illinois Application August 16, 1943, Serial No. 498,754

2 Claims.

This invention relates to cameras, and more particularly to aerial cameras for producing a continuous, true-plan, still photograph of ground terrain from an airplane in flight. The invention is a further development of certain features of the invention shown and described in Letters Patent to Frederick Theodore Sonne, No. 2,307,- 646, dated January 5, 1943.

In cameras of the type aforementioned, a longlength, photographic iilm strip is moved through a photographic field at a speed in exact synchronism with the ground image, thereby insuring production of a continuous, clear, sharp and distortionless true-plan still picture.

The herein invention is a disclosure of only those features which constitute the gist of the claimed improvements and while said improvements are primarily designed and intended for use in connection with aerial cameras, this shall not be viewed with any thought or intention of limiting useful application of the invention to any well known photographic apparatus wherein it is desired to produce like results with the same or equivalent mechanical elements as those herein disclosed.

An object of the invention is to provide apparatus forV the continuous translation at an assigned or predetermined speed of a photographic iilm strip through the photographic eld of the camera in a manner which satisfies exacting photographic requirements and insures production of more accurate photographs than has been possible heretofore with use of prior photographic apparatus. Y

A still further object is to provide reeling and unreeling organizations, the coactive operations of which are carefully calculated to insure translation of the lm through the photographic eld of the-camera at a rate which is always exactly equal to both the rate of ingress of the film to and rate of egress of same from said eld.

Another object is to provide means for gripping the film curvilinearly during angular motion at constant speed of a driven element to thereby avoid slippage of the film in any direction during continuous translation thereof and to hold constant the distance between the lm and an ex- DOSUIB aperture.

Another object is to provide a transmission wherein energy developed at certainV of the elements employed is frictionally employed at others of the elements to insure that the exposed film will be reeled in exact accordance with the rate at which it is fed to a positively driven translating mechanism.

Another object is directed to improve film translating mechanisms operating in coaction with each other to insure an even rate of motion of the nlm at the exposure aperture of the camera regardless of the amount of lm contained at any instant upon the respective magazine and take-up spools of said mechanisms.

The invention further consists in the features of construction, combinations of elements, arrangements of parts, and the coactive relationship of the various organizations of elements as will be more fully set forth herein.

In drawings in which a preferred embodiment of the invention is illustrated,

Figure 1 is a vertical section through the camera; y

Figure 2 is a view similar to Figure 2 with the pay-off and take-up rolls removed for the purpose of clearness;

Figure 3 is a vertical section on an enlarged scale of the friction drive for the take-up spool;

Figure 4 is a view in elevation of the bearing bracket for the take-up and pay-01T spools;

Figure 5 is a section taken on line 5-5 of Figure 4; Y

Figure 6 is a section, taken on the line 6--6 of Fig. 2. Figure 7 is a view partly in elevation and partly in section taken on the line 'l-'l of Fig. 6.

Figure 8 is a view partly in plan and partly in elevation of the exposure aperture, parts being removed and parts being broken away for a clear understanding of the structure;

\ Figure 9 is a section taken substantially on 9-9 of Figure 8, and A Figure 10 is a section taken substantially on the line I0-Ill of Figure 8.

In carrying the invention into practice, use is made ofv a large diameter, positively driven, horizontally mounted drum I0 around which a photographic film strip is trained and from which the im is conducted to a take-up spool Il in exact synchronism with the rate at which the lm is pulled or unwound from a pay-off or magazine spool l2.

All of the aforementioned elements are contained in a housing structure consisting of a lower section I3 and a removable vupper section I4, and, as shown, said lower housing section is formed or rsuitably provided with means i 5 having a mechanism IE for forming at the photo- .graphic field of the camera an exposure aperture of any desired size, across which the film is adapted to be continuously moved at any predetermined speed.

Depending from said means I is a barrel IIa containing a photographic optical system I1, the axis of the lens of which is coaxial relative to the axis of rotation of the drum I9. Said means is provided with a horizontally disposed table or plate I8 which directly underlies said drum III, it being preferred that said plate shall have a slot I9 therein of such form and proportions as to accommodate a portion of the drum in a manner providing only a very scant clearance between the face of said drum and said mechanism I6.

At I9 in the lower housing section I3 is an adjustable speed electric motor of any well known type, the fixed gear on the driven shaft 2| of which constitutes an element in a gear train which includes an intermediate gear 22 meshing with said gear 20 and with a larger diameter gear 23 fixed to one end of said drum I0. Said gear train also includes intermediate intermeshing gears 24 and 25, the former meshing with said drum gear 23 and the latter with a gear 26 of a frictional driven system for the aforestated takeup spool I I. The ratios of the gears of said train is computed so that in coaction with features of the invention to be described presently, the speed of the film through the photographic field of the camera is invariable and always in perfect synchronism with whatever is the speed of the motor I9' at am' instant and whereby the lm speed is likewise in synchronism or proportional to the rate at which the film is wound onto the takeup spool I`I.

Mounted inside the camera housing and preferably attached at 21 to opposite walls of section I3 of said housing are parallel spaced apart plates 28 and 29 These plates provide a common mounting for the spools I I and I2, their adjuncts and the gears 24 and 25.

Referring now to Figure 6 of the accompanying drawings, it is noted that there is secured at 3|) to the inner face of plate 28, a hollow tubular member 3| having ball bearings 32, the inner races of which receive a shaft 33 whose inner end is formed with a circular flange 34 having a stub shaft 35. Said member 3| has preferably formed therewith as an integral part thereof a cylindrical friction element 36, which is complemental to a split friction ring 31. Passing into the space between the meeting ends of said ring is a pin 38, which projects from one side of a rotational inertia mass 39, the medial portion of which is formed with a hub 48. Received in the enlarged bore 4I of said hub is the aforementioned flange 34 of shaft 33, the smaller bore 42 of said hub accommodating the stub shaft 35 in a manner enabling free insertion of said shaft in a coaxial opening 43 in the head 44 of the pay-off spool I2. Formed on the mass 39 are splines 44a adapted to enter correspondingly shaped key ways 45 in said head 44.

Adjustably connecting the meeting ends of said friction ring 31 is an adjusting screw 46 by means of which pressure of the ring against the friction face of said element 36 can be selectively controlled.

It follows that from the manner of mounting the pay-off spool I2, any desired amount of friction can be placed upon said spool and controlled with such nicety and exactness as to prevent over-running of the film strip and whereby the 7 speed at which the nlm is pulled from said spool will be in exact synchronism with the speed of said film through the focal field of the camera. Other structural features of the organization comprising the pay-off spool will be referred to in the description of the take-up spool organization.

The organization of instrumentalities comprising the take-up spool is structurally and functionally similar to the pay-off spool organization. However', in this case, the shaft 33a and its supporting ball bearings 32a are mounted in a member 41, the external form of which is such as to co-act with the gear 26 and provide races for axially spaced apart antifriction bodies 48 and 49. Said gear 26 is formed with an annular friction face 58 and co-acting therewith is a split friction ring 5i, similar, if not identical in every respect to the ring 31 of the pay-off spool organization. The inertia mass 52 has its pin 53 disposed between the meeting ends of said ring 59. As this inertia mass is the same structurally and functionally as the mass 39 and is removably splined to the head 54 of take-up spool II, it will suffice to say that as regards the ends of spools II and i2 adjacent to plate 29, these are each similarly supported by said plate. In Figure 3, the means for supporting the spool I I comprises a pivoted bracket 55 on said plate, the same having a stub shaft 56 adapted when the bracket is swung from the dotted to the full line position shown at Figure 5 to enter a bearing opening 51 in the head 58 of spool I i. When in the full line position, a resilient latchingr device Ela is engageabie therewith and the bracket thereby maintained in a rigid spool supporting position. By the means thus provided, the spools II and I2 are readily removable for replacement purposes, as will be understood.

Referring now to Figures 1, 8, 9 and l0 of the drawings for an understanding of the aperture control mechanism I6, said mechanism comprising a pair of similar guide rails 59 and BIJ, in the former of which are parallel longitudinally disposed channels 6| and 62, the rail 60 having parallel, longitudinally disposed channels 63 and 64. In the channels 6I and 63 of rails 59 and 60 are slidable rack `bars 65 and 66 respectively in mesh with gear pinions 61 and 68 carried by a manually actuable shaft 69. Extending around said shaft is a coil spring 10, one end of which is fixed at 1I to the rail 59, while the other end thereof is fixed at 12 to said shaft. At one end, the shaft has a control knob 13, adapted, when turned in a counter-clockwise direction to impart to a fiat blade 'I4 motion in the direction of arrow a, Figure 8.

The teeth of rack bar 65 also mesh with a pinion 15, the latter, in turn, meshing with a pinion 16 at one end of a Shaft 11. Also upon said shaft 'f1 are pinions 1B and 19, the former meshing with the teeth of a rack bar 30 in channel 62 of rail 59 and the latter meshing with the teeth of rack bar 8| in the channel 64 of rail 6I). Around the shaft 'I1 is a coil spring 82, one end of which is secured at 83 to the shaft and the other end to the rail 60 as at 84. Said spring is wound counterclockwise as distinguished from the clockwise direction of the wound portions of spring 10. The blade 85 of which the rack bars 8|) and 8| are parts is in the same general plane as aforementioned blade 14 and, as shown, these blades have pin and slot connection at 86 with their respective rack bars. Cover strips 81 are removably secured to said rails 59 and 6U and function to maintain necessary interrneshing relationship of the pinion 61, 63, 18 and 19 with their respective rack bars 65, 66, and 8|.

From the above description of the exposure aperture organization, it is appreciated that by faidate virtueof the office of the springs '10 and82, the

blades 14 and 85 tend to assume relative positions such that their meeting or` opposed edges are ln Aabutting relation along a line running parallel to the'longitudinal axis of the drum I0. The arrangement just described is such that the aperture formed between the opposite edges of the blades is perpendicular to the axis of rotation of the drum I0, and that a perpendicular line intersecting the longitudinal center line of the aperture will also intersect the axis of said drum. Relative motion can be imparted to said blades 'by selective control of knob 13 and by reason thereof the size of theV aperture between said Yopposed edges can be regulated at will, the openoccupies upon an airplane, the focal axis of the lens system being perpendicular and intercepted `by the horizontal plane of the aperture blades 14 and 85. Each of the spools II and I2 and the large diameter drum I0 operate about horizontal axes which are parallel to each other. In this figure, it is assumed that the direction of flight is as indicated by the arrow (a) and that the exposure aperture is perpendicular and at right angles to the line of flight. n

When making a photographic picture of terrain from an airplane in flight, certain factors must be considered to the end that well defined pictures will result from exposures made at different altitudes and at varying or predetermined flight speeds. In the instant case and assuming that the photographer lhas made all necessary mathematical computations and therefore knows (l) the altitude of the plane, and (2) has accurately predetermined the speed of the film through the focal field of the camera so that the ground speed and flight speed are in synchronism, it then, merely is necessary to determine the size of the exposure aperture for the shot to be made and to set the motor I9 in operation for continuous translation of the film at a predetermined, invariable speed through said focal field.

The above factors must necessarily be considered and carefully observed at any instant an exposure ismade. To the end that clear, well defined sharp images of objects will be further assured when making a panoramic photograph of the terrain, other important factors must be observed and means employed to prevent faulty or inaccurate or incomplete photographic reproduction of ground objects. It is these last named factors that have been fully considered and studied with the result that heretofore inaccuracies occurring when making aerial photographs can now be avoided or eliminated by the mechanisms or organizations of elements, the structural features of which have now been fully described. The-functional results flowing from said structural elements are, as follows:

The altitude and the flight speed of the plane being known to the operator at the instant a photograph is to be taken, the motor I9 is placed in operation at a speed exactly in synchronism with the ground speed, it being understood that there shall be such discriminate use of the aperture mechanism as to provide in the focal plane of the camera an exposure aperture of appropriate photographic proportions.v The blades 14 and move laterally at equal speeds relative to a line drawn perpendicularly through the lens system thus insuring that regardless of the size of the selected aperture, same will be centrally disposed.

I lRotational motion is simultaneously imparted to the spools I I and I2 and the drum IIJ, the latter having its peripheral face uniformly covered with a soft, friction inducing material such as a good grade of rubber. The film strip F passes downward from the pay-off spool I2, thence under and substantially entirely aroundthe drum III and with its Celluloid side next to the soft peripheral face of said drum. From the drum, the strip is continuously wound onto the frictionally controlled take-'up spool II.

Upon referring to Figures 1 and 6 of the accompanying drawings, it is observed that by reason of a preselected degree of pressure between the element 36 and the ring 31 friction is induced that tends to retard free rotational motion of spool v I2, it being borne in mind that the only energy applied to this spool is the pulling force resulting from positive rotation of drum IU. In this manner there is definite assurance that, at no instant. will more film leave spool I2 than can be timely handled by drum I0. In other words, the rate of delivery of the film to the drum is in absolute synchronism with the rate of delivery ofthe exposed film in the direction of take-up spool II.

Referring now tov Figures 1 and 3, it again is noted that any selected amountof friction can be induced between the friction face of driven gear 26 and the friction ring 5I, whereby spool I I operates in perfect synchronism with drum I0.

By preventing more film being paid from spool I2 than can be paid onto spool II at any instant and by maintaining intimacy of contact between the film and said drum, the distance between the exposure aperture and the nlm is held constant. These niceties come in consequence of a new and novel order of elements and oo-action of the'elements to insure that there never is present a condition of over-running or slippage of the film at the exposure aperture. As a result, thereof, clear, well defined and faithful photographic reproductions of images of ground objects are assured in a manner not heretofore possible with devices of the prior art.

In addition to the main features above referred to, attention is directed to certain structural details. When the upper section I4 of the housing is removed, complete access is had to all operating parts, thus making for quick and convenient threading of the lm through the camera and removal and replacement of film as and when desired.

While the gear train above referred to provides a positive drive for the drum I0, gears 23, 24 and 25 in said train function to transfer rotational motion to spool II by reason of controlled friction between the integral annular friction face 50 of gear 26 and aforementioned friction ring 5I, the latter, for all intents and purposes being a part of the inertia mass 52 to which the spool is splined. Particular stress is placed upon the frictionally driven spool II in combination with the gear driven drum I0 and the frictionally retarded rotary pay-off spool I2, as the precision with which these coordinated organizations function insures that the nlm is never fed faster than it is paid onto spool II and that the speed of the film through the photographic field is held definitely constant or exactly as predetermined by any selected rotational speed of the motor I9.

No claim is made for the mere use of a soft rubber facing for the rotary exposure drum IU, except in the environment in which it is used in carrying out our invention. As rotational motion of spool I2 can be controlled so as to offer any desired amount of friction to its rotation, and as the friction driven means for spool H insures that the peripheral speed of said spool will vary exactly in accordance with the increase in diameter of the coil being formed on the spool, it follows that all moving parts of our camera operate in necessary synchronism. As the film is always being pulled from the spool l2 and onto spool Il, the film wrap which substantially extends entirely around drum I is firmly pressed atwise against the soft rubber face of said drum, thereby securing a positive driven relation of the llm to said drum. This not only serves to insure positive motion of the film across the exposure aperture, but, and in addition thereto to maintain a fixed distance between the aperture and the film and prevent slippage of the film.

While a preferred embodiment of the invention has been shown and described, it will be understood that changes in the form, arrangements, proportions, sizes and details thereof may be made without departing from the scope of the invention as defined by the appended claims.

What we desire to secure by Letters Patent and claim is:

1. In an aerial camera, a vertical casing provided at its lower end with a downwardly opening exposure slit; a downwardly projecting photographic objective secured to the casing beneath said slit; a focal drum mounted in the casing above and with only scant clearance between the slit and the peripheral face or said drum; film pay-off and lm pay-on spools mounted in said casing, from the former of which, the film may be trained about said peripheral face and through the space between said face and said slit thence wound onto said pay-on spool; friction inducing means including a rotatable part detachably splined to the pay-off spool at the axis of rotation thereof; friction inducing means including a rotatable part detachably splined to the pay-on spool at the axis of rotation thereof; means for positively driving the focal drum at any assigned angular velocity and for positively driving the rotatable part of the second named friction inducing means; and means by which friction at the respective friction inducing means can be controlled and the film maintained under constant tension such that the surface of contact of the film with the peripheral face of said focal drum and the distance between the slit and the effective focal point of said drum are each thereof invariable during translation of the lm at any selected angular velocity, and whereby the rate of translation of the nlm across said slit is the same as that at which the nlm is paid from the pay-olfspool and the rate at which it is wound onto said pay-on spool.

2. In an aerial camera, a vertical casing provided at its lower end with a downwardly opening exposure slit; a downwardly projecting photographic objective secured to the casing beneath said slit; a focal drum mounted in the casing above and with only scant clearance between the slit and the peripheral face of said drum; nlm pay-oil and lm pay-on spools mounted in said casing, from the former of which, the film may be trained about said peripheral face and through the space between said face and said slit thence wound onto said pay-on spool; friction inducing means including a rotatable part splined to the pay-off spool at the axis of rotation thereof; friction inducing means including a rotatable part splined to the pay-on spool at the axis of rotation thereof; means for positively driving the focal drum at any assigned angular velocity and for positively driving the rotatable part of the second named friction inducing means; and means by which friction at the respective friction inducing means can be controlled and the film maintained under constant tension such that the surface of contact of the film with the peripheral face of said focal drum and the distance between the slit and the effective focal point of said drum are each thereof invariable during translation of the film at any selected angular velocity, and whereby the rate of translation of the lm across said slit is the same as that at which the film is paid from the pay-off spool and the rate at which it is wound onto said pay-on spool.

FREDERICK THEODORE SONNE. VCTOR SUSSIN. 

